The present invention relates to fields of engineering which make use of the combustion of fuels in reciprocating piston engines, whether these are of the linear type with free pistons or of the crank mechanism type with crankshafts.
More particularly, the present invention relates to engines which use a new combustion process, described by the present inventor in Patent Application PCT/TB 97/01362, which is carried out within one or more precombustion chambers opening into the cylinders, exploiting the dynamics of the expansion of the gases contained in them to keep the flame fronts generated by the combustion practically fixed, in other words, in practice, to allow the flame fronts to move only a few tens of millimeters from the points of ignition, which are located near the apertures through which the said precombustion chambers open, as stated, into the corresponding cylinders, which can be continuations of each other in the case of internal combustion linear generators, or adjacent to each other as is usually the case in engines with crankshafts.
The combustion process described above has the principal object and advantage of causing combustion to take place in such a way that the flame temperature remains sufficiently low at all points, to reduce the formation of nitrogen oxides to a minimum.
To keep the flame in the desired conditions, the inventor has proposed, in the aforementioned patent application, that the electrode be maintained in a coaxial position at the opening of the corresponding process, to form a baffle of the desired thickness which acts as a thermal flywheel for the flame which passes through it at speed, using various apertures formed in it, the flame being formed and expelled from the precombustion chamber as a result of the expansion of the gases (fuel and air mixtures) contained separately in the precombustion chamber.
However, investigations and tests carried out in this area have revealed limits on the shape and arrangement of the parts of a precombustion chamber and electrode system as described above, since, owing to the form of the gas expansion curve, an electrode in the form of a baffle is suitable for its purpose within a relatively limited period, in which the flame front is essentially fixed.
Moreover, in the case of a precombustion chamber with an aperture of limited diameter (less than 18 mm for example), there is a risk that the temperature of the flame in the shape of a cylindrical ring which develops in the cylinder or cylinders may exceed the predetermined limit in some areas, because of the exchange of heat between opposite areas of the ring.
To avoid all these problems, while achieving the desired object of maintaining the flame temperature conveniently low at all points, but allowing the flame front to move to a significant extent, if necessary, with respect to the aperture of the precombustion chamber, and keeping the charge of mixture confined without the occurrence of any undesired dilution in any of its areas as a result of excessive turbulence, the inventor of the present solution has devised a precombustion chamber and electrode assembly in which the electrode has the shape of a solid of revolution, contained coaxially in the part of the precombustion chamber which is saturated with the fuel, which has a longitudinal extension such that, throughout the period in which the combustion takes place, the said flame front, while moving as a result of the dynamics of the gases, always remains in contact with the electrode.
The subject of the present invention is a precombustion chamber and electrode assembly as described below. A more detailed description of some preferred examples of embodiments of an assembly according to the invention will now be given; these examples are not to be considered restrictive or limiting in respect of other embodiments which may be produced by a person skilled in the art.